Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
Recording apparatuses such as a facsimile, a copier, and a printer are configured to record an image on a recording medium such as a paper, a cloth, and an OHP sheet, and can be categorized into an inkjet system, a wire dot system, a thermal system, and similar system depending on the recording system. Furthermore, inkjet recording systems can be categorized into a serial type and a line head type. In the serial type, recording is performed while a recording head scans a recording medium. In the line head type, recording is performed by a recording head secured to the apparatus main body.
When a recording medium is printed using the recording apparatus, the recording medium displaced in the direction (the recording medium width direction) perpendicular to the conveyance direction causes displacement of the printing position for each recording medium. Accordingly, for the case of bookbinding after printing, the printing position accuracy for each page is required to be high. In particular, when an ink-jet recording apparatus is used, the ink is likely to soak into the recording medium such that a back copy occurs. Accordingly, a higher accuracy (for example, zero point several mm or less) is required in the printing position accuracy during duplex printing.
Therefore, a typically-used image forming apparatus includes an end-portion position detection sensor on a conveyance belt to convey a paper sheet (recording medium). The end-portion position detection sensor detects the positions of the widthwise end portions of the paper sheet using reflected lights. In this image forming apparatus, the positions of the widthwise end portions of the paper sheet are detected based on the intensity difference between the reflected light from the conveyance belt and the reflected light from the paper sheet.
Here, another disclosed image forming apparatus includes an end-portion position detection sensor, which detects the positions of the widthwise end portions of the paper sheet, on the conveyance belt to convey the paper sheet.